举例

import tensorflow as tf
import numpy as np
BATCH_SIZE = 8
seed = 23455

rng = np.random.RandomState(seed)
X = rng.rand(32,2)
Y = [[int(x0 + x1 < 1)] for (x0, x1) in X]
print('X:\n', X)
print('Y:\n', Y)

x = tf.placeholder(tf.float32, shape=(None, 2))
y_ = tf.placeholder(tf.float32, shape=(None, 1))

w1 = tf.Variable(tf.random_normal([2, 3], stddev=1, seed=1))
w2 = tf.Variable(tf.random_normal([3, 1], stddev=1, seed=1))

a = tf.matmul(x, w1)
y = tf.matmul(a, w2)

loss = tf.reduce_mean(tf.square(y-y_))
train_step = tf.train.GradientDescentOptimizer(0.001).minimize(loss)

with tf.Session() as sess:
init_op = tf.global_variables_initializer()
sess.run(init_op)
print('w1:\n', sess.run(w1))
print('w2:\n', sess.run(w2))
print('\n')

STEPS = 3000
for i in range(STEPS):
start = (i*BATCH_SIZE) % 32
end = start + BATCH_SIZE
sess.run(train_step, feed_dict={x: X[start:end], y_: Y[start:end]})
if i % 500 == 0:
total_loss = sess.run(loss, feed_dict={x: Y, y_: Y})
print("After %d training step(s), loss on all data is %g" % (i, total_loss))

print('\n')
print('w1:\n', sess.run(w1))
print('w2:\n', sess.run(w2))